Polishing head and CMP device

Abstract

Provided are a polishing head and a CMP device that are capable of adjusting the pressure in an accommodating pocket when a wafer is being polished. The CMP device includes the polishing head. The polishing head polishes the wafer by rotating while pressing the wafer against a polishing pad 14 to which slurry is being supplied. The polishing head 20 includes: a head body 25 having an air chamber 46 to which pressurized air is supplied; a template retainer 50 having an accommodating pocket 51 for accommodating the wafer; and a membrane film 45 provided between the head body 25 and the template retainer 50 and having suction-attachment holes 48 between the air chamber 46 and the accommodating pocket 51. The template retainer 50 has discharge passages 53 for discharging pressurized air that has flowed from the air chamber 46 into the accommodating pocket 51 to an external space.

Description

Polishing Head and CMP Apparatus

[0001] The present disclosure relates to a polishing head for holding a wafer to be polished and a CMP apparatus including the polishing head.

[0002] There is a CMP apparatus that polishes a workpiece such as a wafer by chemical mechanical polishing (CMP). The CMP apparatus includes a polishing head for holding the wafer and a polishing pad against which the wafer is pressed. The CMP apparatus supplies a slurry, which is a mixture of an abrasive and various chemicals, to the polishing pad and rotates the polishing head and the polishing pad to polish the wafer.

[0003] The polishing head has, for example, an air chamber controlled to negative pressure or positive pressure and a housing pocket in which the wafer is housed, as described in Patent Document 1. The air chamber and the housing pocket are partitioned by a membrane film. The membrane film has suction holes formed therein that communicate the air chamber and the housing pocket. The wafer in the housing pocket contacts the membrane film by suction when the air chamber is at negative pressure and is pressed against the polishing pad by the membrane film when the air chamber is at positive pressure.

[0004] Japanese Patent Application Laid-Open No. 2013-94918

[0005] During polishing, the air in the air chamber at positive pressure may flow into the housing pocket through the suction holes of the membrane film. As a result, when the pressure in the housing pocket increases, it becomes difficult to press the wafer against the polishing pad, resulting in a decrease in the polishing rate.

[0006] The polishing head that solves the above problems polishes the wafer by rotating it while pressing it against a polishing pad to which a slurry is supplied. The polishing head comprises a head body having an air chamber to which pressurized air is supplied, a template retainer having a storage pocket for accommodating the wafer, and a membrane film provided between the head body and the template retainer and having adsorption holes between the air chamber and the storage pocket, wherein the template retainer has a discharge passage for discharging the pressurized air that has flowed from the air chamber into the storage pocket to the outside space.

[0007] A CMP apparatus that solves the above problems comprises a platen having a polishing pad to which a slurry is supplied, and a polishing head that polishes a wafer by rotating while pressing the wafer against the polishing pad. The polishing head comprises a head body having an air chamber to which pressurized air is supplied, a template retainer having a storage pocket for accommodating the wafer, and a membrane film provided between the head body and the template retainer and having adsorption holes that connect the air chamber and the storage pocket, and the template retainer has a discharge passage for discharging the pressurized air that has flowed from the air chamber into the storage pocket to the outside space.

[0008] According to this disclosure, changes in pressure within the storage pocket can be adjusted during wafer polishing.

[0009] Figure 1 is a perspective view showing a schematic configuration of one embodiment of a CMP apparatus. Figure 2 is a cross-sectional view showing a schematic configuration of one embodiment of a polishing head. Figure 3 is a plan view showing an example of a membrane film. Figure 4(a) is a schematic cross-sectional view showing the state in which a wafer is adsorbed onto the membrane film, and Figure 4(b) is a schematic cross-sectional view showing the state in which a wafer is pressed against the polishing pad. Figure 5 is a schematic cross-sectional view showing how pressurized air is discharged to the outside space through the discharge passage. Figure 6 is a bottom view of one embodiment of a template retainer. Figure 7 is a cross-sectional view showing an example of a discharge passage. Figure 8(a) is a diagram showing the schematic configuration of a first polishing pad, and Figure 8(b) is a diagram showing the schematic configuration of a second polishing pad. Figure 9(a) is a graph showing an example of experimental results when using a NoLine template retainer, Figure 9(b) is a graph showing an example of experimental results when using a 12Line template retainer with a discharge passage of 0.2 mm in depth, Figure 9(c) is a graph showing an example of experimental results when using a 12Line template retainer with a discharge passage of 0.3 mm in depth, Figure 9(d) is a graph showing an example of experimental results when using a 12Line template retainer with a discharge passage of 0.4 mm in depth, and Figure 9(e) is a graph showing an example of experimental results when using a 12Line template retainer with a discharge passage of 0.5 mm in depth. Figure 10(a) is a graph showing an example of experimental results when using a 24Line template retainer with a discharge passage of 0.2 mm depth, Figure 10(b) is a graph showing an example of experimental results when using a 24Line template retainer with a discharge passage of 0.3 mm depth, Figure 10(c) is a graph showing an example of experimental results when using a 24Line template retainer with a discharge passage of 0.4 mm depth, and Figure 10(d) is a graph showing an example of experimental results when using a 24Line template retainer with a discharge passage of 0.5 mm depth.Figure 11(a) is a graph summarizing an example of experimental results when using a NoLine template retainer, Figure 11(b) is a graph summarizing an example of experimental results when using a 12Line template retainer, and Figure 11(c) is a graph summarizing an example of experimental results when using a 24Line template retainer. Figure 12 is a cross-sectional view showing an example of a modified discharge passage. Figure 13 is a cross-sectional view showing another example of a modified discharge passage. Figure 14 is a cross-sectional view showing another example of a modified discharge passage.

[0010] An embodiment of a polishing head and a CMP (Chemical Mechanical Polishing) apparatus will be described with reference to Figures 1 to 11. As shown in Figure 1, the CMP apparatus 10 has a platen 11 and a polishing head 20. The platen 11 has a disc shape. The platen 11 is connected to a rotating shaft 12. The platen 11 rotates in the direction of arrow 13 in Figure 1 as the rotating shaft 12 rotates by the drive of a drive source (not shown). A polishing pad 14 is attached to the upper surface of the platen 11. The polishing pad 14 is configured to be replaceable. The polishing pad 14 is, for example, a foamed polyurethane pad in which a nonwoven fabric pad is laminated on a cushion layer. A slurry, which is a mixture of an abrasive and a chemical, is supplied onto the polishing pad 14 from a nozzle (not shown).

[0011] The polishing head 20 is formed in the shape of a disc with a smaller diameter than the platen 11. The polishing head 20 is connected to a rotating shaft 21 located above it. The polishing head 20 rotates in the direction of arrow 22 about the rotational axis 20A as the rotating shaft 21 rotates due to the drive of a drive source (not shown). The polishing head 20 is configured to be able to move up and down in the height direction Z by a lifting device (not shown). The polishing head 20 is configured to be able to hold a wafer 15 (see Figure 4).

[0012] The CMP apparatus 10 supplies slurry to the polishing pad 14 to form a slurry layer on the surface of the polishing pad 14, and rotates the platen 11 and the polishing head 20. The CMP apparatus 10 then polishes the wafer 15 by pressing the wafer 15, which is held by the polishing head 20, against the polishing pad 14.

[0013] (Polishing head) As shown in Figure 2, the polishing head 20 comprises a head body 25, a membrane film 45, and a template retainer 50.

[0014] The head body 25 includes a shaft connecting member 26, a carrier 27, a carrier pressing portion 33, a retainer pressing member 35, a retainer holder 36, a snap ring 38, and a retainer pressing portion 41.

[0015] The shaft connecting member 26 is connected to the rotating shaft 21. The shaft connecting member 26 is configured to rotate together with the rotating shaft 21. The shaft connecting member 26 is connected to a carrier 27 located below the shaft connecting member 26 via a connecting portion 28. The carrier 27 is configured to rotate together with the shaft connecting member 26.

[0016] A carrier recess 30 is formed in the lower part of the carrier 27, with the rim 29 as its peripheral wall. The carrier 27 has a plurality of first air passages 31 that open into the carrier recess 30. The first air passages 31 open to the peripheral edge of the carrier recess 30. More specifically, one end of the first air passages 31 opens into the carrier recess 30 at equal intervals in the circumferential direction around the rotation axis 21 of the carrier 27. The other end of the first air passages 31 is connected to an air control means 32.

[0017] The carrier pressing section 33 is provided between the axial connecting member 26 and the carrier 27. The carrier pressing section 33 is an airbag or the like that inflates when air is supplied from an air supply source (not shown). The pressure of this air is adjusted by a regulator (not shown). The carrier pressing section 33 presses the carrier 27 according to the pressure of the supplied air, thereby pressing the wafer 15 housed in the housing pocket 51 against the polishing pad 14. Details of the housing pocket 51 will be described later.

[0018] The retainer pressing member 35 and the retainer holder 36 are provided to surround the carrier 27. The retainer pressing member 35 is provided to surround the portion of the carrier 27 above the rim 29. The retainer holder 36 is provided to abut the bottom surface of the retainer pressing member 35 and surround the rim 29 of the carrier 27. The carrier 27 is surrounded by the retainer pressing member 35 and the retainer holder 36, forming a second air passage 37 in the polishing head 20. The second air passage 37 connects the space formed by the carrier recess 30 with the external space of the polishing head 20.

[0019] The retainer pressing member 35 and the retainer holder 36 may be detachably connected by a snap ring 38. The snap ring 38 connects the retainer pressing member 35 and the retainer holder 36 by fitting into fitting recesses formed on the outer circumference of each of the retainer pressing member 35 and the retainer holder 36. After the connection of the retainer pressing member 35 and the retainer holder 36, the snap ring 38 is protected by being covered by a ring cover 39. The head body 25 does not necessarily have to be equipped with a snap ring 38 and a ring cover 39. The retainer pressing member 35 may be connected to the retainer holder 36, or the retainer pressing member 35 and the retainer holder 36 may be integrated.

[0020] The retainer holder 36 has a mounting portion 40. The mounting portion 40 is located below the rim 29 of the carrier 27. The peripheral edge of the membrane film 45 and the peripheral edge of the template retainer 50 are arranged on the mounting portion 40.

[0021] The retainer pressing portion 41 is located between the shaft connecting member 26 and the carrier 27, and is positioned outside the carrier pressing portion 33. The retainer pressing portion 41 is an airbag or the like that inflates when air is supplied from an air supply source (not shown). The pressure of this air is adjusted by a regulator (not shown). The retainer pressing portion 41 presses the template retainer 50 against the polishing pad 14 via the retainer pressing member 35 and the retainer holder 36, according to the pressure of the supplied air.

[0022] The membrane film 45 is formed, for example, in a disc shape (see Figure 3). The membrane film 45 is provided so that its peripheral edge is sandwiched between the retainer holder 36 and the template retainer 50. The membrane film 45 is provided so as to cover the carrier recess 30 from below. The membrane film 45 has adsorption holes 48 that communicate with the air chamber 46 and the storage pocket 51, which will be described later. The membrane film 45 is formed of an elastic material. The membrane film 45 is made of, for example, polyethylene terephthalate (PET) resin, fluororesin, or polyphenylene sulfide (PPS) resin. The membrane film 45 is attached to the mounting portion 40 via an elastic adhesive layer, which is not shown. The space surrounded by the carrier recess 30 and the membrane film 45 is the air chamber 46. In other words, the air chamber 46 is the space between the carrier recess 30 and the membrane film 45 in the height direction Z.

[0023] As shown in Figure 3, the membrane film 45 has a plurality of adsorption holes 48. The adsorption holes 48 communicate with the air chamber 46 and the containment pocket 51, which will be described later. The adsorption holes 48 are arranged around the rotational axis 20A. Note that the arrangement of the adsorption holes 48 shown in Figure 3 is just one example, and the arrangement of the adsorption holes 48 is not limited to that shown in Figure 3.

[0024] The template retainer 50 is formed in an annular shape (see Figure 6). The template retainer 50 has a thickness slightly greater than the thickness of the wafer 15 to be polished. The template retainer 50 has an inner circumferential surface 50a located inside the rim 29 of the carrier 27. The space surrounded by the inner circumferential surface 50a, i.e., the internal space of the template retainer 50, is a storage pocket 51 in which the wafer 15 is housed. The template retainer 50 is made of, for example, glass epoxy, polyetheretherketone (PEEK) resin, or polyphenylene sulfide (PPS) resin. The template retainer 50 has a membrane film 45 attached to it by an adhesive layer such as double-sided tape. The template retainer 50 may be disposed in the mounting portion 40 with the membrane film 45 attached, or it may be disposed in the mounting portion 40 by attaching it to the membrane film 45 attached to the mounting portion 40. The template retainer 50 may be directly attached to the retainer holder 36, or it may be integrated with the retainer holder 36.

[0025] The template retainer 50 can form a storage pocket 51 to match the wafer 15 to be polished. Therefore, by changing the template retainer 50, wafers of various sizes can be polished using one type of head body 25. For example, the template retainer 50 is attached when polishing a 4-inch wafer using a head body 25 designed for polishing 6-inch wafers. In this case, the polishing of the wafer 15 can be performed more stably, for example, because the center of gravity of the head body is more stable than that of a head body specifically designed for polishing 4-inch wafers. In the case of a normal polishing head designed for polishing 6-inch wafers, instead of the template retainer 50, a retainer ring may be provided below the retainer holder 36, having an inner surface at approximately the same position as the inner surface of the retainer holder 36 in the radial direction.

[0026] As shown in Figure 4(a), when the polishing head 20 transports the wafer 15, the air chamber 46 is controlled to a negative pressure by suction from the air control means 32. At this time, air from the outside space is introduced into the air chamber 46 through the second air passage 37, and the membrane film 45 attracts the wafer 15 housed in the storage pocket 51.

[0027] As shown in Figure 4(b), when polishing the wafer 15, the air chamber 46 is controlled to a positive pressure by the supply of pressurized air by the air control means 32. At this time, excess air in the air chamber 46 is discharged to the outside space through the second air passage 37, and the pressure in the storage pocket 51 is maintained at a normal pressure, such as atmospheric pressure, which is lower than the pressure in the air chamber 46. In the normal pressure state, when the pressure in the storage pocket 51 is at the normal pressure, the membrane film 45 flexes into the storage pocket 51, thereby appropriately pressing the wafer 15 against the polishing pad 14. The flow rate of pressurized air supplied to the air chamber 46 is called the air float flow rate.

[0028] (Discharge passage) As shown in Figure 5, the template retainer 50 has a discharge passage 53. The discharge passage 53 is a passage that communicates the storage pocket 51 with the outside space. As indicated by the arrow in Figure 5, the discharge passage 53 is a passage for adjusting the pressure in the storage pocket 51 to the normal pressure by discharging the pressurized air that flows into the storage pocket 51 from the air chamber 46 during the polishing of the wafer 15 to the outside space.

[0029] Even if the template retainer does not have an exhaust passage, if the polishing pad 14 has grooves of sufficient depth, the pressurized air that flows from the air chamber 46 into the storage pocket 51 is discharged to the outside space through the grooves of the polishing pad 14. In other words, the discharge of pressurized air through the grooves of the polishing pad 14 maintains the storage pocket 51 in a normal pressure state.

[0030] However, if the groove depth of the polishing pad 14 decreases due to wear or other reasons, the pressurized air that flows into the storage pocket 51 becomes less able to be discharged to the outside space, causing the pressure in the storage pocket 51 to become higher than the normal pressure. When the storage pocket 51 is under such abnormal pressure conditions, the membrane film 45 can no longer properly press the wafer 15. The discharge passage 53 is a passage that more reliably discharges the pressurized air that flows from the air chamber 46 into the storage pocket 51 to the outside space, regardless of the condition of the groove of the polishing pad 14.

[0031] As shown in Figure 6, the discharge passage 53 has an inlet 53a on the inner circumferential surface 50a of the template retainer 50 and an outlet 53b on the outer circumferential surface 50c. The outlet 53b is formed such that, for example, at least a portion of it is located at a height higher than the slurry layer formed on the surface of the polishing pad 14. The discharge passage 53 is a groove formed in the bottom surface 50b of the template retainer 50. This groove extends, for example, in the height direction Z from the bottom surface 50b of the template retainer 50 to a height higher than the slurry layer. The discharge passage 53 extends linearly in the radial direction of the template retainer 50 around the rotational axis 20A. The template retainer 50 has a plurality of discharge passages 53. The plurality of discharge passages 53 are formed at equal intervals around the rotational axis 20A. Specifically, the discharge passages 53 are formed radially at 30° intervals around the rotational axis 20A.

[0032] As shown in Figure 7, the cross-sectional shape of the discharge passage 53 is rectangular, with a width W greater than the depth D. The discharge passage 53 has groove bottom surfaces 53c at various points between the inlet 53a and the outlet 53b, at a position higher than the slurry layer.

[0033] (Function) As shown in Figure 5, the discharge passage 53 discharges the pressurized air that has flowed from the air chamber 46 into the containment pocket 51 through the adsorption holes 48 to the outside space. By adjusting the pressure in this way, the pressure in the containment pocket 51 is maintained at, for example, atmospheric pressure.

[0034] (Depth of discharge passage) The inventors conducted an experiment to compare the removal rate of wafers 15 using a template retainer 50 in which a discharge passage 53 is formed.

[0035] The experiments and results conducted by the inventors will be described with reference to Figures 8 to 11. The inventors conducted the experiments with pressurized air flowing from the air chamber 46 into the containment pocket 51. In this experiment, the thermal oxide film on a silicon wafer having a diameter of 4 inches and a thickness of 525 μm was used as the target for polishing. In this experiment, polishing was performed for a predetermined time while the polishing pads were sharpened synchronously. The main experimental conditions are shown in Table 1.

[0036] The inventors prepared a first polishing pad and a second polishing pad as polishing pads.

[0037] As shown in Figure 8(a), the first polishing pad 55 has perforated grooves 56 formed in the rigid foamed polyurethane layer. As shown in Figure 8(b), the second polishing pad 57 has perforated grooves 56 and XY grid grooves 58 formed in the rigid foamed polyurethane layer.

[0038] The inventors have prepared nine types of template retainers. Specifically, for depths D = 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm, the inventors have prepared 12-line template retainers in which discharge passages 53 are formed radially at 30° intervals around the rotational axis 20A, and 24-line template retainers in which discharge passages 53 are formed radially at 15° intervals around the rotational axis 20A. The thickness of each template retainer is 1 mm, and the width W of the discharge passages 53 is 2 mm. In addition, as a reference example, the inventors have prepared a No-Line template retainer in which no discharge passages 53 are formed.

[0039] Figure 9(a) shows an example of experimental results when using the NoLine template retainer. Figures 9(b), 9(c), and 9(d) show an example of experimental results when using the first polishing pad.

[0040] Figures 10(a), 10(b), 10(c), and 10(d) show an example of experimental results when using the second polishing pad. In Figures 9 and 10, the vertical axis represents the polishing rate. The horizontal axis represents the radial coordinates with the rotation center of the polishing head 20 (rotation center axis 20A) as the origin.

[0041] Figure 11(a) shows an example of experimental results when using a NoLine template retainer. Figure 11(b) shows an example of experimental results when using a 12Line template retainer. Figure 11(c) shows an example of experimental results when using a 24Line template retainer.

[0042] In Figures 11(a) to 11(c), the vertical axis represents the polishing rate. The polishing rate on the vertical axis represents the average value of the polishing rate obtained at each coordinate in the radial direction with the rotation center of the polishing head 20 (rotation center axis 20A) as the origin. In Figures 11(b) and 11(c), the horizontal axis represents the depth. In Figures 11(a) to 11(c), the bar graph on the left shows the experimental results with the first polishing pad, and the bar graph with dots on the right shows the experimental results with the second polishing pad.

[0043] As shown in Figures 9(a) and 11(a), when using the NoLine template retainer, the first polishing pad was hardly able to polish. This is thought to be because, with the first polishing pad having only P grooves, pressurized air in the housing pocket 51 does not easily escape through the NoLine template retainer, and the pressure in the housing pocket 51 is higher than the normal pressure. On the other hand, a polishing rate of about 350 nm / min was obtained with the second polishing pad. This is thought to be because, with the second polishing pad having XY grid grooves, pressurized air in the housing pocket 51 escapes more easily through the NoLine template retainer than with the first polishing pad, and the pressure in the housing pocket 51 is more easily maintained at the normal pressure. Based on these differences in polishing rates, the inventors hypothesized that the pressure in the housing pocket 51 can be adjusted to the normal pressure by forming a discharge passage 53 in the template retainer 50.

[0044] As shown in FIGS. 9(b) to 9(e) and FIG. 11(b), when the 12Line template retainer was used, in the first polishing pad, polishing rates of 250 nm / min or more were obtained for each of depths D = 0.3 mm, 0.4 mm, and 0.5 mm. On the other hand, for a depth D = 0.2 mm, the polishing rate was 250 nm / min or less. This is because the outlet 53b of the discharge passage 53 is temporarily blocked by slurry, the polishing pad, and / or a highly viscous fluid or the like, making it difficult for the pressurized air to be discharged through the discharge passage 53. In the second polishing pad, polishing rates of about 350 nm / min were obtained for each of depths D = 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.

[0045] As shown in FIGS. 10(a) to 10(d) and FIG. 11(c), when the 24Line template retainer was used, in the first polishing pad, polishing rates of 250 nm / min or more were obtained for each of depths D = 0.3 mm, 0.4 mm, and 0.5 mm. On the other hand, for a depth D = 0.2 mm, similar to the 12Line template retainer, the polishing rate was 250 nm / min or less. In the second polishing pad, polishing rates of 300 nm / min or more were obtained for each of depths D = 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. Also, when compared with the 12Line template retainer, it was found that although equivalent polishing rates were obtained in the first polishing pad, overall, slightly lower polishing rates were obtained in the second polishing pad.

[0046] From the above experimental results, when the depth D of the discharge passage 53 is less than 0.3 mm, the polishing rate is approximately 200 nm / min when polishing with the first polishing pad, and it was found that the polishing pad capable of obtaining a polishing rate of 250 nm / min or more is limited to the second polishing pad. On the other hand, when the depth D of the discharge passage 53 is 0.3 mm or more, it was found that a polishing rate of 250 nm / min or more can be obtained in both the first and second polishing pads of different types. Further, in the range where the depth D of the discharge passage 53 is 0.3 mm or more, it was found that even if the shape of the polishing pad or the template retainer changes over time due to wear or the like, a decrease in the polishing rate can be suppressed.

[0047] From the above, the depth D is preferably 0.3 mm or more so that the groove bottom surface 53c is disposed at a position higher than the slurry layer. The width W is preferably 1 mm to 3 mm so that the flow path cross-sectional area of the discharge passage 53 is ensured. More specifically, the depth D is preferably 0.5 mm and the width W is preferably 2 mm.

[0048] The effects of the present embodiment will be described. (1) The template retainer 50 is formed with a discharge passage 53 for discharging the pressurized air flowing from the air chamber 46 into the storage pocket 51. Thereby, even if pressurized air flows from the air chamber 46 into the storage pocket 51, the pressure in the storage pocket 51 can be maintained at a pressure lower than that of the air chamber 46, for example, atmospheric pressure. That is, even if pressurized air flows into the storage pocket 51, the change in the pressure in the storage pocket 51 can be adjusted.

[0049] (2) The template retainer 50 has an inlet 53a of the discharge passage 53 on the inner peripheral surface 50a. The template retainer 50 has an outlet 53b of the discharge passage 53 at a height higher than the slurry layer supplied to the surface of the polishing pad 14. Thereby, it becomes difficult for the outlet 53b of the discharge passage 53 to be blocked by the slurry. As a result, the pressurized air flowing into the storage pocket 51 can be efficiently discharged to the external space.

[0050] (3) The template retainer 50 has an outlet 53b of the discharge passage 53 on its outer surface 50c. As a result, the outlet 53b of the discharge passage 53 is exposed to the outside space, and the back pressure of the discharge passage 53 becomes atmospheric pressure. As a result, the pressurized air that has flowed into the storage pocket 51 can be efficiently discharged to the outside space.

[0051] (4) The discharge passage 53 is formed by a groove formed on the bottom surface 50b of the template retainer 50. This makes it easy to form the discharge passage 53 in the template retainer 50.

[0052] (5) The depth D of the discharge passage 53 is 0.3 mm or more. This makes it possible to obtain the required polishing rate regardless of the specifications of the polishing pad 14. In addition, it is possible to suppress an excessive decrease in the polishing rate even if the polishing pad 14 or the template retainer 50 wears down.

[0053] (6) When the pressurized air in the storage pocket 51 is discharged through the discharge passage 53, the slurry and pressurized air in the discharge passage 53 act as resistance. In contrast, the discharge passage 53 has a rectangular cross-sectional shape with a width W in the range of 1 mm to 3 mm.

[0054] With this configuration, for example, compared to the case where the flow path cross-section is a semicircular shape with the same diameter, the flow path cross-sectional area of ​​the discharge passage 53 becomes larger, and the proportion of the flow path cross-section of the discharge passage 53 that is located away from the surface of the polishing pad 14 becomes larger. As a result, the discharge passage 53 is less likely to be blocked by slurry, and the state in which the containment pocket 51 is in communication with the outside space is more easily maintained, thereby reducing the resistance of the discharge passage 53 to the discharge of pressurized air.

[0055] (7) The discharge passage 53 extends linearly in the radial direction of the template retainer 50. This allows the discharge passage 53 to connect the inner circumferential surface 50a and the outer circumferential surface 50c of the template retainer 50 via the shortest route. As a result, the pressure loss in the discharge passage 53 is reduced, making it easier for the pressurized air in the containment pocket 51 to be discharged into the outside space, and also making it easier for the slurry in the discharge passage 53 to be discharged into the outside space by the centrifugal force of the template retainer 50.

[0056] (8) The discharge passages 53 are formed radially at 30° intervals around the rotational axis 20A of the template retainer 50. As a result, the discharge passages 53 are evenly distributed around the rotational axis 20A, allowing pressurized air in the storage pocket 51 to be efficiently discharged to the outside space. Furthermore, the processing load when forming multiple discharge passages 53 can be reduced.

[0057] (9) The head body 25 includes a retainer pressing member 35 surrounding the carrier 27, a retainer holder 36 which is pressed toward the polishing pad 14 by the retainer pressing member 35 and to which the membrane film 45 and template retainer 50 are attached, and a snap ring 38 which fits between the retainer pressing member 35 and the retainer holder 36 and detachably connects the retainer pressing member 35 and the retainer holder 36.

[0058] With this configuration, the retainer holder 36, to which the membrane film 45 and template retainer 50 are attached, can be removed from the retainer pressing member 35 by removing the snap ring 38. Therefore, the replacement of the membrane film 45 and template retainer 50 can be performed in a workspace suitable for such replacement work. As a result, the installation of the membrane film 45 and template retainer 50 onto the retainer holder 36 can be easily performed.

[0059] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they are not technically contradictory. In the above embodiment, the discharge passage 53 is formed by a groove formed on the bottom surface of the template retainer 50. However, the discharge passage is not limited to this, and is formed in the template retainer 50 so as to connect the storage pocket 51 with the external space.

[0060] For example, as shown in Figure 12, the discharge passage 60 may be formed on the upper surface 50d of the template retainer 50 and may be a groove extending from the inner circumferential surface 50a to the outer circumferential surface 50c. Even with this configuration, pressurized air flowing into the containment pocket 51 can be discharged to the outside space, as indicated by the arrows in the figure. The flow path cross-section of the discharge passage 60 may be rectangular or semicircular. Furthermore, the flow path cross-sectional area of ​​the discharge passage 60 is preferably set according to the airflow rate, as the discharge passage 60 is less affected by the slurry.

[0061] Alternatively, as shown in Figure 13, the discharge passage 61 may be formed on the upper surface 50d of the template retainer 50 and may be a groove extending from the inner circumferential surface 50a to below the second air passage 37. In this case, the discharge passage 61 has an outlet on the upper surface 50d of the template retainer 50. The membrane film 45 also has a connecting hole 62 that connects the second air passage 37 and the discharge passage 61. Even with this configuration, as indicated by the arrows in the figure, pressurized air flowing into the containment pocket 51 can be discharged to the outside space through the second air passage 37. The flow path cross-section of the discharge passage 61 may be rectangular or semicircular. Furthermore, the flow path cross-sectional area of ​​the discharge passage 61 is preferably set according to the airflow rate, since the discharge passage 61 is less affected by the slurry.

[0062] The discharge passages 53 are formed radially at 30° intervals around the rotational axis 20A of the template retainer 50. However, the discharge passages 53 may also be formed radially at 15° intervals or at 45° intervals around the rotational axis 20A of the template retainer 50. Furthermore, the discharge passages 53 do not have to be formed at equal intervals around the rotational axis 20A of the template retainer 50.

[0063] The discharge passage 53 extends linearly in the radial direction of the template retainer 50. However, it is not limited to this; for example, the discharge passage 53 may extend linearly in a direction intersecting the radial direction of the template retainer 50, or it may extend in a curved direction opposite to the rotational direction of the template retainer 50.

[0064] - The flow path cross-section of the discharge passage 53 is not limited to a rectangular shape. For example, the flow path cross-section of the discharge passage 53 may be semicircular or triangular. - As shown in Figure 14, the discharge passage 63 may be a through-hole that penetrates the inside of the template retainer 50, with an inlet on the inner circumferential surface 50a and an outlet on the outer circumferential surface 50c. In this configuration, it is preferable that the outlet 63b of the discharge passage 63 is formed at a height of 0.3 mm or more relative to the bottom surface of the template retainer 50. The flow path cross-section of the discharge passage 63 may also be circular. It is preferable that the flow path cross-sectional area of ​​the discharge passage 63 be set according to the airflow rate.

[0065] - The width W of the discharge passage 53 can be changed as appropriate, for example, according to the size of the template retainer 50 itself. - The depth D of the discharge passage 53 can be changed as appropriate, for example, according to the thickness of the template retainer 50.

[0066] 10...CMP device, 11...platen, 12...rotating shaft, 13...arrow, 14...polishing pad, 15...wafer, 20...polishing head, 20A...rotating center axis, 21...rotating shaft, 22...arrow, 25...head body, 26...shaft connecting member, 27...carrier, 28...connecting part, 29...rim, 30...carrier recess, 31...first air passage, 32...air control means, 33...carrier pressing part, 35...retainer pressing member, 36...retainer holder 37...Second air passage, 38...Snap ring, 39...Ring cover, 40...Mounting part, 41...Retainer pressing part, 45...Membrane film, 46...Air chamber, 48...Adsorption hole, 50...Template retainer, 50a...Inner circumferential surface, 50b...Bottom surface, 50c...Outer circumferential surface, 50d...Top surface, 51...Storage pocket, 53, 60, 61, 63...Discharge passages, 53a...Inlet, 53b, 63b...Outlet, 53c...Groove bottom surface, 62...Connection hole.

Claims

1. A polishing head for polishing a wafer by rotating it while pressing it against a polishing pad supplied with slurry, comprising: a head body having an air chamber supplied with pressurized air; a template retainer having a storage pocket for accommodating the wafer; and a membrane film provided between the head body and the template retainer, having adsorption holes communicating with the air chamber and the storage pocket, wherein the template retainer has a discharge passage for discharging the pressurized air that has flowed from the air chamber into the storage pocket to the outside space.

2. The polishing head according to claim 1, wherein the inlet of the discharge passage is formed on the inner circumferential surface of the template retainer, and the outlet of the discharge passage is formed at a height higher than the slurry layer formed on the surface of the polishing pad.

3. The polishing head according to claim 2, wherein the outlet of the discharge passage is formed on the outer circumferential surface of the template retainer.

4. The polishing head according to claim 3, wherein the discharge passage is a groove formed on the bottom surface of the template retainer, and the groove extends in the height direction from the bottom surface of the template retainer to the height.

5. The polishing head according to claim 3 or 4, wherein the height is 0.3 mm or more relative to the bottom surface of the template retainer.

6. The polishing head according to claim 5, wherein the discharge passage has a rectangular cross-sectional shape with a width in the range of 1 mm to 3 mm.

7. The polishing head according to claim 6, wherein the discharge passage extends linearly in the radial direction of the template retainer.

8. The polishing head according to claim 7, wherein the discharge passage is one of a plurality of discharge passages formed radially at 30° intervals around the rotational axis of the template retainer.

9. A CMP apparatus comprising: a platen having a polishing pad to which a slurry is supplied; and a polishing head for polishing a wafer by rotating while pressing the wafer against the polishing pad, wherein the polishing head comprises: a head body having an air chamber to which pressurized air is supplied; a template retainer having a storage pocket for accommodating the wafer; and a membrane film provided between the head body and the template retainer and having adsorption holes that communicate the air chamber and the storage pocket, and the template retainer having a discharge passage for discharging the pressurized air that has flowed from the air chamber into the storage pocket to the outside space.

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